KR102593639B1 - Polarizing plate and optical display apparatus comprising the same - Google Patents

Abstract

A polarizing plate including a polarizer and a protective layer formed on at least one surface of the polarizer, wherein the polarizing plate includes a first region and a second region in an image display area, and the first region and the second region have light transmittance at the same wavelength. are different from each other, the first region has a light transmittance of 50% to 80%, the first region has a color value a* value of -13 to 2, and a color value b* value of 1 to 35, and An optical display device including this is provided.

Description

Polarizing plate and optical display device including the same {POLARIZING PLATE AND OPTICAL DISPLAY APPARATUS COMPRISING THE SAME}

The present invention relates to a polarizing plate and an optical display device including the same.

Polarizers are included in optical display devices for the purpose of displaying images or improving image quality. In mobile displays such as cell phones, a polarizer may be used as an intermediate path for an image sensor such as a camera to take a photo or video.

Referring to (A) of FIG. 2, the optical display device includes a display panel 50 including a base layer 51 and a plurality of light emitting elements 52, a polarizing plate 40 formed on the display panel 50, and a polarizing plate. (40) It may be provided with a cover glass 60 formed on the display panel 50 and an image sensor 10 disposed partially penetrating the display panel 50 . The image sensor 10 is disposed partially penetrating the polarizer 40 . The area 40a of the polarizer 40 corresponding to the image sensor corresponds to an image non-display area that does not display images. In order to secure a space for penetration of the image sensor 10, the polarizer 40 was processed using a physical punching method. However, in this case, the image in the image display area 40b may be poor due to cracks in the area around the punching area to form the area 40a of the polarizer 40.

Referring to (B) of FIG. 2, an area that allows the image sensor 10 to operate by chemical and optical methods instead of physically punching the polarizer 40 as shown in (A) of FIG. 2 A method of including a polarizer 70 having an area 70a and an area 70b, which is an image display area, was considered. In this case as well, the area 70a corresponds to the image non-display area. In addition, there is a problem in that the display panel 50 including the light emitting element is separated due to the image sensor 10, making processing difficult.

Recently, as shown in Figure 2 (A) and Figure 2 (B), in order to secure space for placing the image sensor, instead of allowing the image sensor to partially penetrate the display panel with the light emitting element, it penetrates the display panel. An optical display device that places an image sensor at the bottom of the display panel is being developed. In this case, an area of the polarizer corresponding to the image sensor must also be able to perform the image display function at the same time, the image sensor must not be visible while performing the image display function, and it must be able to create a clear image during shooting. However, there were limitations in using conventional polarizers in the above optical display devices.

The background technology of the present invention is described in Japanese Patent Publication No. 2014-081482, etc.

The object of the present invention is applied to an optical display device in which an image sensor such as a camera is formed in the image display area, and when the image sensor is not used, the visibility of the image sensor can be reduced from the outside and the image display function can be performed. When used, a polarizing plate is provided that can achieve the effect of increasing the clarity of the image.

The present invention provides an optical display device including the polarizing plate of the present invention.

One aspect of the present invention is a polarizer.

1. The polarizer includes a polarizer and a protective layer formed on at least one surface of the polarizer, the polarizer includes a first region and a second region in an image display area, and the first region and the second region are at the same wavelength. The light transmittance is different, the first region has a light transmittance of 50% to 80%, the color a* value of the first region is -13 to 2, and the color b* value is 1 to 35.

In 2.1, the first region may have a polarization degree of 25% to 80%.

In 3.1-2, the first region may have an iodine content of 0.01% by weight to 5% by weight.

In 4.1-3, the first area may have an image display function and an image capturing function.

In 5.1-4, the second area may have a light transmittance of 40% or more and less than 50%.

The optical display device of the present invention includes the polarizing plate of the present invention.

The present invention is applied to an optical display device in which an image sensor such as a camera is formed in the image display area, and when the image sensor is not used, the image display function can be performed by lowering the visibility of the image sensor from the outside. At this time, a polarizing plate was provided, which had the effect of increasing the clarity of the image.

The present invention provided an optical display device including the polarizing plate of the present invention.

Figure 1 shows a cross-sectional view of an optical display device equipped with a polarizing plate of the present invention.
Figure 2 shows a cross-sectional view of a conventional optical display device equipped with an image sensor.
Figure 3 shows the color coordinate evaluation results of the first region of the polarizers of Example 1 and Comparative Examples 1 and 2.

With reference to the attached drawings and examples, the present invention will be described in detail so that those skilled in the art can easily practice it. The present invention may be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts not related to the description are omitted, and the same names are used for identical or similar components throughout the specification. The length and size of each component in the drawings are for illustrative purposes only, and the present invention is not limited to the length and size of each component depicted in the drawings.

In this specification, “upper” and “lower” are defined based on the drawings, and “upper” may be changed to “lower” and “lower” may be changed to “upper” depending on the viewing angle.

In this specification, “light transmittance” and “polarization degree” of a polarizing plate refer to values measured at a wavelength of 380 nm to 780 nm, preferably at a wavelength of 550 nm. The “light transmittance” refers to total light transmittance rather than orthogonal light transmittance.

Regarding “light transmittance of the first region” in this specification, the light transmittance of the first region is the same throughout the region at the same wavelength. However, if the light transmittance is not the same throughout the region even at the same wavelength, the light transmittance of the first region means the average light transmittance.

Regarding “light transmittance of the second region” in this specification, the light transmittance of the second region is the same throughout the region at the same wavelength. However, if the light transmittance is not the same throughout the region even at the same wavelength, the light transmittance of the second region means the average light transmittance.

In this specification, “average light transmittance” means the average value of light transmittance in the area where the average light transmittance is to be measured. For example, the average light transmittance can be obtained by arbitrarily designating a plurality of points among the area where the average light transmittance is to be measured and calculating the average value of the light transmittance obtained at those points.

In this specification, when describing a numerical range, “X to Y” means more than X and less than Y (X≤ and ≤Y).

The polarizing plate of one embodiment of the present invention includes a polarizer and a protective layer formed on at least one surface of the polarizer. In one embodiment, the polarizing plate may include a polarizer and a protective film formed on both sides of the polarizer, respectively. In another embodiment, the polarizing plate may include a polarizer and a protective film formed only on one side of the polarizer.

The polarizing plate includes a first area and a second area within the image display area. The 'image display area' refers to the area where an image is displayed when a polarizer is mounted on an optical display device. The image display area of the polarizer may comprise 90% to 100% of the polarizer, preferably 100%. In one embodiment, the polarizer may not include an image non-display area.

The first area and the second area have different light transmittances at the same wavelength. Accordingly, the first area and the second area perform both image display functions, but unlike the second area, the first area can also perform an external image capture function using an image sensor such as a camera, which will be described in detail below.

The first region has a light transmittance of 50% to 80%. Within the above range, it is possible to achieve the effect of lowering the visibility of the image sensor from the outside and implementing an image display function when the image sensor is not used, while increasing the clarity of the image through the image sensor when the image sensor is used. In particular, in the present invention, the light transmittance of the first region can achieve the above-described effect in a stacked configuration of an image sensor in an optical display device, a panel containing a light-emitting element, and a polarizer. A display panel containing a light-emitting element and an image sensor are sequentially arranged in the lower part of the first area, so that an image display function and an external image capture function can be performed simultaneously. One embodiment of the optical display device of the present invention is described in more detail below.

The second area only performs an image display function and is unrelated to the image display function by the image sensor in the optical display device. Therefore, the second area has lower light transmittance than the first area.

In one embodiment, the difference between the light transmittance of the first area and the light transmittance of the second area may be 5% to 30%, preferably 10% to 30%. In the above range, the camera is not visible and the image difference between the first area where the camera is located and the second area where the camera is not reduced can be reduced to implement a uniform image across the entire screen.

The second area may have a light transmittance of 40% to 50%, specifically 40% to 45%. In the above range, the image display function can be well implemented.

The first region and the second region may have the same degree of polarization, but preferably, considering the manufacturing process of the first region described in detail below, the first region has a lower degree of polarization than the second region.

In one embodiment, the first region may have a polarization degree of 25% to 80%, specifically 28% to 70%. Within the above range, there may be an effect of not interfering with object recognition by the camera. In one embodiment, the second region may have a polarization degree of 90% or more, specifically 90% to 100%. Within the above range, there may be an effect of preventing reflection from external light.

Hereinafter, a polarizing plate of an embodiment of the present invention will be described with reference to FIG. 1. Figure 1 shows a cross-sectional view of an optical display device equipped with a polarizing plate of the present invention.

Referring to FIG. 1, the polarizer 100 includes a first region 110 and a second region 120.

The entire first area 110 and the second area 120 of the polarizer 100 are disposed between the display panel 150 and the cover glass 200. The display panel 150 can perform an image display function by including a light-emitting element 152. Accordingly, the first area 110 and the second area 120 are included in the image display area.

The optical display device has an image sensor 250 provided in a portion of the lower part of the display panel 150 corresponding to the first area 110. Accordingly, the first area 110 reduces the visibility of the image sensor from the outside and implements an image display function when the image sensor 250 is not used, and provides an image capture function through the image sensor when the image sensor 250 is used. This can achieve the effect of increasing the clarity of the image. The light transmittance of 50% to 80% of the first area 110 performs all of the above-described functions in the stacked configuration of the image sensor 250 in the optical display device, the display panel 150 containing a light emitting element, and the polarizer 100. It has been adjusted so that it can be implemented.

The first area 110 may have an area ratio of the polarizer, preferably less than 10% of the entire first area 110 and the second area 120 . In the above range, the image sensor function can be displayed.

The first region 110 may be circular, oval, prismatic, or amorphous, but is not particularly limited thereto.

The position where the first region 110 is formed in the polarizer is not particularly limited and can be adjusted depending on the position of the image sensor 250 in the optical display device.

The first area 110 can better implement the effect of the present invention by adjusting the color values a* and color values b* based on color coordinates. That is, the first area 110 must be able to display images continuously together with the second area 120, and when using an image sensor, images can be captured clearly. For this purpose, the light transmittance, color value a*, and color value b* of the first area 110 were adjusted together.

In one embodiment, the first region has a color a* value of -13 to 2, preferably -10 to 2, more preferably -4 to 2, and a color b* value of 1 to 1 according to color coordinates. 35, preferably 15 to 35. Within the above range, the first area must be able to display images continuously together with the second area, and when using an image sensor, images can be captured clearly.

The “color coordinates” can be obtained by the color coordinate evaluation method based on CIE 1976 L*a*b* values.

Hereinafter, a manufacturing method of an embodiment of a polarizer having a first region 110 and a second region 120 will be described.

The polarizing plate of the present invention is manufactured by manufacturing a laminate in which a protective layer is formed on at least one surface of the polarizer (on which the first region and the second region are not formed) and the polarizer (on which the first region and the second region are not formed), It can be manufactured by forming the first region by irradiating a pulsed UV laser with a wavelength of 200 nm to 1000 nm to the part of the laminate where the first region is to be formed. The area that is not irradiated with the pulse UV laser becomes the second area. Pulse UV laser irradiation with a wavelength of 200 nm to 1000 nm can not only create a first region with light transmittance of 50% to 80%, but can also simultaneously implement the above-mentioned color coordinates.

The polarizer (in which no first or second regions are formed) includes a polyvinyl alcohol-based film dyed with at least one dichroic material selected from iodine and dichroic dye and stretched. The polarizer (in which no first or second regions are formed) may have a thickness of 3 μm to 50 μm, specifically 3 μm to 30 μm. Within the above range, it can be used in a polarizing plate.

The polarizer (in which the first region and the second region are not formed) can be manufactured by a conventional method known to those skilled in the art.

First, a dyed and stretched polyvinyl alcohol-based film is manufactured.

Dyed and stretched polyvinyl alcohol-based films can be manufactured by dyeing, stretching, crosslinking, and complementary color processes. In the method for manufacturing the polarizer of the present invention, the order of dyeing and stretching is not limited. That is, the polyvinyl alcohol-based film may be dyed and then stretched, stretched and then dyed, or dyeing and stretching may be performed simultaneously.

The polyvinyl alcohol-based film can be a conventional polyvinyl alcohol-based film used in manufacturing a conventional polarizer. Specifically, a film formed of polyvinyl alcohol or its derivatives can be used. The degree of polymerization of polyvinyl alcohol may be 1000 to 5000, the degree of saponification may be 80 mol% to 100 mol%, and the thickness may be 1㎛ to 30㎛, specifically 3㎛ to 30㎛, and in the above range , can be used to manufacture thin polarizers.

Polyvinyl alcohol-based films may be washed with water and swollen before being dyed or stretched. By washing the polyvinyl alcohol-based film with water, foreign substances on the surface of the polyvinyl alcohol-based film can be removed. By swelling the polyvinyl alcohol-based film, dyeing or stretching of the polyvinyl alcohol-based film can be improved. As known to those skilled in the art, the swelling treatment can be performed by leaving the polyvinyl alcohol-based film in an aqueous solution in a swelling bath. The temperature of the swelling tank and the swelling treatment time are not particularly limited. The swelling tank may further contain boric acid, inorganic acid, surfactant, etc., and their contents may be adjusted.

A polyvinyl alcohol-based film can be dyed by dyeing the polyvinyl alcohol-based film in a dyeing bath containing at least one type of iodine or dichroic dye. In the dyeing process, the polyvinyl alcohol-based film is immersed in a dyeing solution, which may be an aqueous solution containing iodine and a dichroic dye. Specifically, iodine is provided from iodine-based dyes, and iodine-based dyes may include one or more of potassium iodide, hydrogen iodide, lithium iodide, sodium iodide, zinc iodide, lithium iodide, aluminum iodide, lead iodide, and copper iodide. . The dyeing solution may be an aqueous solution containing 1% to 5% by weight of one or more types of iodine or dichroic dye. Within the above range, it can have a polarization degree within a predetermined range and be used in a display device.

The temperature of the dyeing tank may be 20°C to 45°C, and the dyeing tank immersion time of the polyvinyl alcohol-based film may be 10 seconds to 300 seconds. A polarizer with a high degree of polarization can be implemented within the above range.

By stretching the dyed polyvinyl alcohol-based film in a stretching bath, the polyvinyl alcohol-based film can have polarization properties by aligning one or more of iodine and dichroic dyes. Specifically, stretching can be done by both dry stretching and wet stretching methods. Dry stretching may include interroll stretching, compression stretching, heat roll stretching, etc., and wet stretching may be performed in a wet stretching bath containing water at 35°C to 65°C. The wet stretching bath may increase the stretching effect by further including boric acid.

The polyvinyl alcohol-based film may be stretched at a predetermined stretching ratio, specifically so that the total stretching ratio is 5 to 7 times, specifically 5.5 to 6.5 times, and the cutting phenomenon of the polyvinyl alcohol-based film stretched in the above range. , wrinkles, etc. can be prevented, and a polarizer with increased polarization degree and transmittance can be implemented. Stretching is uniaxial stretching, which means that it can be stretched in one stage, but it can also prevent breakage while manufacturing a thin polarizer by performing multi-stage stretching, such as 2-stage or 3-stage stretching.

In the above, the order of dyeing and then stretching the polyvinyl alcohol-based film was described, but dyeing and stretching may be performed in the same reaction tank.

Before stretching the dyed polyvinyl alcohol-based film or after dyeing, the stretched polyvinyl alcohol-based film may be crosslinked in a crosslinking tank. Crosslinking is a process that allows one or more types of iodine or dichroic dye to be dyed more strongly on a polyvinyl alcohol-based film, and boric acid can be used as a crosslinking agent. To increase the crosslinking effect, phosphoric acid compounds, potassium iodide, etc. may be further included.

Dyed and stretched polyvinyl alcohol-based films can be treated with complementary colors in complementary colors. Complementary color treatment involves immersing the dyed and stretched polyvinyl alcohol-based film in a complementary color bath containing a complementary color solution containing potassium iodide. Through this, the color value of the polarizer can be lowered and the iodine anion I ^- in the polarizer can be removed to improve durability. The temperature of the complementary color bath may be 20°C to 45°C, and the complementary color bath immersion time of the polyvinyl alcohol-based film may be 10 seconds to 300 seconds.

Next, a laminate is manufactured by forming a protective layer on at least one side of the dyed and stretched polyvinyl alcohol-based film. Formation of the protective layer can be performed by conventional methods known to those skilled in the art.

The protective layer is formed on at least one side of the polarizer and may be a photocurable coating layer or a protective film.

The protective film may be a protective film commonly used as a protective film for a polarizer. For example, the protective film may be cellulose-based including triacetylcellulose, polyester-based including polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, cyclic polyolefin-based, and polycarbonate. A protective film made of one or more of the following resins: polyethersulfone, polysulfone, polyamide, polyimide, polyolefin, polyarylate, polyvinyl alcohol, polyvinyl chloride, and polyvinylidene chloride. It can be included. The protective film may have a thickness of 10 μm to 100 μm, for example, 10 μm to 60 μm. The lamination can be carried out with an adhesive, using conventional methods known to those skilled in the art.

Then, a pulse UV laser with a wavelength of 200 nm to 1000 nm is irradiated to the portion of the laminate where the first region is to be formed to form the first region.

Pulse UV laser with a wavelength of 200nm to 1000nm can increase light transmittance in the area irradiated by the laser by decomposing the iodine and dichroic dyes by transitioning the iodine and dichroic dyes dyed on the polarizer from the ground state to the excited state. .

However, even if a pulse UV laser in the wavelength range of 200 nm to 1000 nm is irradiated, dichroic substances such as iodine and dichroic dye are present in the polarizer corresponding to the first region after irradiation.

In one embodiment, the first region may have an iodine content of 0.01% to 5% by weight, specifically 0.01% to 1% by weight. Within the above range, there may be an effect of increasing transmittance while minimizing discoloration. The “iodine content” is a content including iodine I ₂ and ionic forms of iodine (I ^- , I ₃ ^- , I ₅ ^- , etc.).

The present invention is different from the existing method of treating the polarizer with an acid or alkaline solution to completely remove dichroic substances such as iodine and dichroic dyes in the polarizer, thereby increasing the light transmittance to more than 80%. In addition, the present invention requires no post-processing after irradiation compared to the method of forming a region with high light transmittance on the polarizer by processing the polarizer with an existing femtosecond laser, nanosecond laser, etc., and the boundary between the first region and the second region is clear. It is different from

Specifically, in the wavelength range of 200 nm to 1000 nm, a pulse laser of 200 nm to 800 nm may be preferably selected.

A pulse laser with a wavelength of 200 nm to 1000 nm may be irradiated with a voltage of 400 V to 750 V. A pulse laser with a wavelength of 200 nm to 1000 nm may be irradiated with a pulse period of 300 μs to 600 μs (irradiation time for one irradiation). A pulse laser with a wavelength of 200 nm to 1000 nm may be irradiated with an irradiation energy density of 2.0 J/cm ² to 5.0 J/cm ² . A pulse laser with a wavelength of 200 nm to 1000 nm can be irradiated with a laser intensity of 5 kw/cm ² to 30 kw/cm ² when irradiated once. In the above range, the light transmittance of the present invention can be reached from 50% to 80%, and there can be no surface carbonization of the processed surface of the polarizer due to heat. The “irradiation energy density” refers to the irradiation energy per pulse per unit area of the region of high light transmittance in the polarizer.

In one embodiment, when irradiating with a 460 μs pulse laser with a wavelength of 200 nm to 1000 nm, the irradiation may be performed for 0.4 seconds to 400 seconds, for example, 1 second to 40 seconds in the wavelength range. Within the above range, a more neutral, colorless, high-transmittance part can be formed by increasing the irradiation time or number of times under the above irradiation conditions without thermal deformation of the polarizer and the protective film.

A pulse laser with a wavelength of 200 nm to 1000 nm can be irradiated 1 to 20 times. Within the above range, a more neutral, colorless, high-transmittance part can be formed by increasing the irradiation time or number of times under the above irradiation conditions without thermal deformation of the polarizer and the protective film.

The polarizer in which the first and second regions are formed may have a thickness of 3㎛ to 50㎛, specifically 3㎛ to 30㎛. Within the above range, it can be used in a polarizing plate.

Hereinafter, a manufacturing method of another embodiment of a polarizer having the first region 110 and the second region 120 will be described.

The polarizing plate of the present invention is irradiated with a pulse UV laser with a wavelength of 200 nm to 1000 nm to the portion of the polarizer where the first region is to be formed (where the first region and the second region are not formed), and a protective layer is applied on at least one side of the polarizer. It can be manufactured through a forming step. The area irradiated with the pulse UV laser becomes the first area, and the area not irradiated with the pulse UV laser becomes the second area. Substantially the same as the method of manufacturing the polarizer of an embodiment of the present invention, except that instead of irradiating the pulsed UV laser to the laminate of the polarizer and the protective layer, the pulsed UV laser is irradiated to the polarizer (where the first region and the second region are not formed). do.

Hereinafter, an optical display device according to an embodiment of the present invention will be described.

The optical display device of the present invention includes the polarizing plate of the present invention. The optical display device may include an organic light emitting display device, etc.

Referring to Figure 1, the optical display device of the present invention will be described in more detail.

Referring to FIG. 1, the optical display device includes a display panel 150 on which a base layer 151 and a plurality of light-emitting elements 152 are formed, a polarizing plate 100 formed on the display panel 150, and a polarizing plate 100. It may include a formed cover glass 200 and an image sensor 250 disposed below the display panel 150.

The polarizing plate 100 includes a first region 110 and a second region 120 and includes the polarizing plate of the present invention. Both the first area 110 and the second area 120 form an image display area of the optical display device.

In the first area 110, the light emitting elements 151 are formed less densely than in the second area 120. Through this, it is possible to implement the image display function by the image sensor 250 and simultaneously perform the image display function by the display panel 150.

The image sensor 250 is formed in the lower part of the first area 110. The image sensor 250 may include, but is not limited to, a camera.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the present invention and should not be construed as limiting the present invention in any way.

Specific specifications of the ingredients used in the following examples and comparative examples are as follows.

(1) Material of polarizer: polyvinyl alcohol-based film (VF-PE3000, Kuraray, Japan, thickness: 30㎛)

(2) Protective film: Triacetylcellulose film (KC4UYW, Konica, Japan, thickness 40㎛)

Example 1

The polyvinyl alcohol-based film washed with water was subjected to swelling treatment in a water swelling tank at 30°C.

The polyvinyl alcohol-based film that passed through the swelling tank was treated in a dyeing tank at 30°C containing an aqueous solution containing 3% by weight of potassium iodide for 30 to 200 seconds. The polyvinyl alcohol-based film that had passed through the dyeing tank was passed through a wet cross-linking tank containing an aqueous solution at 30°C to 60°C containing 3% by weight of boric acid. A polarizer was manufactured by stretching the polyvinyl alcohol-based film that had passed through the crosslinking tank in an aqueous solution at 50°C to 60°C containing 3% by weight of boric acid so that the total stretching ratio was 6 times. A laminate was manufactured by attaching a protective film to both sides of the manufactured polarizer using an adhesive (Z-200, Nippon Goshei).

The laminate was cut to a predetermined size, and a pulse UV laser with a wavelength of 200 nm to 800 nm was irradiated only to the area where the first region was to be formed in the laminate under the conditions shown in Table 1 below, thereby manufacturing a polarizing plate with the first region formed. The area of the polarizer that is not irradiated with the pulse UV laser becomes the second area.

Examples 2 to 4

A polarizing plate in which a first region and a second region were formed was manufactured in the same manner as in Example 1, except that the pulse UV laser was irradiated under the conditions shown in Table 1 below.

Comparative Example 1

In Example 1, a polarizing plate with a first region and a second region was manufactured by performing the same method as Example 1, except that the pulse UV laser was irradiated under the conditions shown in Table 2 below.

Comparative Example 2

In Example 1, a polarizing plate with a first region and a second region was manufactured by performing the same method as Example 1, except that the pulse UV laser was irradiated under the conditions shown in Table 2 below.

Comparative Example 3

In Comparative Example 3, a polarizing plate was manufactured in the same manner as Example 1, except that the first region was formed by a chemical method. In Example 1, the protective film was peeled off from the polarizer, and a surface mask in which a circular through hole with a diameter of 50 mm was formed was bonded to the exposed surface of the polarizer. The polarizer was immersed in a 5 mol/L aqueous solution of sodium hydroxide (alkaline aqueous solution) for 7 seconds. Afterwards, it was immersed in 0.1 m/l hydrochloric acid for 5 seconds. The obtained result was dried in an oven at 60°C and the surface mask was peeled off. Accordingly, a polarizer in which the first region was formed was manufactured. A polarizer was manufactured by attaching a PET film with a pressure-sensitive adhesive layer having a thickness of 5 μm to the polarizer as a surface protection film. The first region of the polarizer manufactured from this had a light transmittance of 91.71%. Even if the alkaline aqueous solution conditions were different, a polarizing plate with a light transmittance exceeding 80% could not be obtained.

Comparative Example 4

In Example 1, only the portion corresponding to the first region was cut using a laser cutting machine, and as a result, a polarizing plate with the first region punched out was manufactured.

The following physical properties were evaluated for the polarizing plates manufactured in Examples and Comparative Examples, and the results are shown in Table 1, Table 2, and Figure 3.

(1) Light transmittance of the first and second regions (unit: %): Light transmittance using JASCO V730 at a wavelength of 550 nm for each of the first and second regions among the polarizers manufactured in Examples and Comparative Examples. was measured.

(2) Polarization degree of the first region and the second region (unit: %) Measure the polarization degree at a wavelength of 550 nm for each of the first region and the second region among the polarizers manufactured in the examples and comparative examples using JASCO V730. did.

(3) Color coordinates of the first region Color value a* value, color value b* value: Color of the first region among the polarizers manufactured in Examples and Comparative Examples using a UV-VIS spectrophotometer V7100 (JASCO) The value was evaluated.

(4) Whether the camera is visible and the image clarity by the camera: A camera was placed at the bottom of the area corresponding to the first area of the polarizer, and whether it was visible by the camera and the resulting image were observed with the naked eye at the top of the polarizer. If the lens of the camera is not observed and only the difference in polarization between the first and second areas is confirmed and the clarity of the image taken by the camera is excellent ◎, If the lens of the camera is observed and the clarity of the image taken by the camera is excellent X1, If the difference between the first and second areas was not confirmed and the clarity of the image taken by the camera was poor, it was evaluated as X2.

Example One 2 3 4 Voltage (V) 606 606 535 535 Pulse period (μs, irradiation time for one irradiation) 300 300 460 460 Intensity of laser per irradiation (kw/cm ² ) 13 13 8.7 8.7 Irradiation energy density (J/cm ² ) 3.31 3.31 3.77 3.77 Number of investigations (times) One 8 One 8 Irradiation cycle (Hz) - 0.125 - 0.125 light transmittance Area 1 56.68 59.23 62.32 66.38 2nd area 43.24 43.24 43.24 43.24 Polarization Area 1 55.45 50.12 30.45 28.85 2nd area 99.99 99.99 99.99 99.99 first area
Color coordinates a* 1.83 1.26 -2.29 -2.01 b* 20.58 19.52 28.15 27.71 Visibility and clarity ◎ ◎ ◎ ◎

Comparative example One 2 3 4 Voltage (V) 950 400 - - Pulse period (μs, irradiation time for one irradiation) 50 700 - - Intensity of laser per irradiation (kw/cm ² ) 40 3.2 - - Irradiation energy density (J/cm ² ) 1.89 5.51 - - Number of investigations (times) One 8 - - Irradiation cycle (Hz) - 0.125 - - light transmittance Area 1 44.21 84.91 91.71 - 2nd area 43.24 43.24 43.24 43.24 Polarization Area 1 97.05 20.18 0.1073 - 2nd area 99.99 99.99 99.99 99.99 first area
Color coordinates a* -0.98 -1.31 -0.48 - b* 3.18 11.06 1.44 - Visibility and clarity X2 X1 X1 X1

As shown in Table 1 above, when mounted on an optical display device, the polarizer of the present invention can lower the visibility of the image sensor from the outside and perform an image display function when the image sensor is not used, and when the image sensor is used, the polarizer of the present invention can perform an image display function. The effect of increasing clarity was achieved. In addition, as shown in FIG. 3, the first area is not easily visible even on a black screen, so the image display function can be prevented from occurring. Referring to FIG. 3, there are three circular color coordinate evaluation images, of which the leftmost one is the evaluation result of Example 1.

On the other hand, as shown in Table 2, in Comparative Example 1, which has a first area that exceeds the light transmittance of the present invention, the image sensor is not visible on a black screen, but there is a problem in the image sensor recognizing an external light source. As shown in FIG. 3, Comparative Examples 1 and 2 have a problem in that the first area is easily visible on a black screen. In addition, Comparative Example 3, which formed a region with high light transmittance using a conventional chemical method, and Comparative Example 4, which used a conventional punching method, could not obtain the effect of the present invention.

Simple modifications or changes to the present invention can be easily implemented by those skilled in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (6)

A polarizing plate including a polarizer and a protective layer formed on at least one surface of the polarizer,
The polarizer includes a first area and a second area in an image display area,
The first area and the second area have different light transmittances at the same wavelength,
The first region has a light transmittance of 50% to 80%,
The first region has a color value a* value of -13 to 2 and a color value b* value of 1 to 35,
A polarizing plate in which the first region has a polarization degree of 25% to 80%.
delete The polarizing plate of claim 1, wherein the first region has an iodine content of 0.01% to 5% by weight.
The polarizing plate according to claim 1, wherein the first area has an image display function and an image taking function.
The polarizing plate of claim 1, wherein the second region has a light transmittance of 40% to 50%.
An optical display device comprising the polarizing plate of any one of claims 1, 3, and 5.